Device and method for delivery of long wavelength laser energy to a tissue site

ABSTRACT

A laser energy delivery device is provided that is suitable for irradiating a body tissue with relatively long wavelength laser energy in the presence of an aqueous liquid without significant absorption of the laser energy by the liquid. The device includes an elongate hollow sheath that has an open aperture at its distal end portion and closed at its proximal end, a laser energy conduit such as an optical fiber or hollow wave guide, within the sheath, the distal end of the conduit being disposed near the open aperture at the distal end portion of the sheath, and the proximal end of the conduit being adapted for connection to a source of long wavelength laser energy. The sheath also includes an inlet port, spaced from the proximal end of the sheath, and adapted to receive and deliver a biologically compatible gas through the sheath to a body tissue site in contact with the open distal end of the sheath. In use, the open aperture at the distal end portion of the sheath is positioned in contact with a body tissue site. Gas, such as carbon dioxide, infused through the sheath displaces an aqueous liquid from the region between the distal end portion of the sheath and the tissue. Laser energy emitted from the distal end portion of the conduit passes through the substantially liquid-free region at the distal end of the sheath and impinges on the tissue to be irradiated. The laser energy can be used to ablate, vaporize, coagulate or shrink tissue at the target zone without interference from aqueous liquids, which tend to absorb relatively large amounts of long wavelength laser energy and reduce the efficiency of tissue ablation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of copending U.S. patentapplication Ser. No. 10/324,897, filed on Dec. 20, 2002.

FIELD OF THE INVENTION

The present invention relates to laser energy delivery devices and theirmethod of use in an aqueous environment. More particularly, theinvention relates to laser energy delivery devices useful for deliveringlaser energy at wavelengths of about 1,300 to 11,000 nanometers, to abody tissue site with reduced interference from surrounding aqueousfluid media.

BACKGROUND OF THE INVENTION

Lasers that emit light energy at wavelengths in the range of about 1,300to about 11,000 nanometers (long wavelength or “LW” laser energy) areexcellent vaporizers of tissue, since their energy is highly absorbed bywater, a major constituent of mammalian tissue. When exposed to suchlong wavelength laser energy, the water in the tissue is rapidly heatedand converted to steam, causing ablation or vaporization of the tissue.These properties make long wavelength lasers particularly useful fornonsurgical removal or reduction of tissue.

Typically, laser energy is delivered to a tissue site via an opticalfiber or an optical wave guide device adapted for transmission of longwavelength laser energy. The emitting end of the fiber optic or waveguide is placed in close proximity to the desired tissue site. Anendoscope is first positioned inside a duct, body cavity, hollow organor surgically created passageway at the tissue site. The energy emittingend of the optical fiber or wave guide is then threaded through achannel in the endoscope to place the emitting end of the optical fiberor wave guide in the optical position near the tissue. Typically a fiberoptic viewing device is also positioned at the working end of theendoscope to view the tissue site as it is being irradiated with laserlight energy and to verify the correct positioning of the emitted laserenergy.

However, when water, saline, or other aqueous liquid is infused throughthe endoscope to provide a clear field of view of the tissue inside aduct, body cavity, hollow organ, or surgically created passageway, viathe fiber optical viewing device, a substantial amount of the laserenergy is wasted. The aqueous liquid between the distal end of theoptical fiber and the target tissue absorbs a substantial part of thelight energy and creates a steam bubble, which acts as an “opticalcavity.” The remainder of the laser energy passes through the steambubble and vaporizes or ablates the target tissue. However, as the steambubble collapses between pulses of laser energy, liquid flows back intothe space between the distal end of the optical fiber and the targettissue, requiring some of the laser energy to again be consumed inrecreating the steam bubble between the optical fiber and the tissue,diminishing the amount of laser energy reaching the target tissue.

The above phenomenon was first described by Jeffrey M. Isner et al. in“Mechanism of laser ablation in an absorbing fluid field,” Lasers Surg.Med. 1988;8(6):543-54, and is commonly referred to as the “Moses Effect”or “parting the water.”

Holmium lasers emitting long wavelength light were used in the mid tolate 1990's to resect prostate tissue, as described above. However,while the procedure produced benefits comparable to a trans-urethralresection of the prostrate or “TURP” procedure, in which a wire loop isheated by radiofrequency (“RF”) energy to cut-out swaths of prostatetissue, the laser procedure typically took about 45 minutes to an hourfor a small (20-30 gram prostate) and longer than an hour for largerprostates. As a result, the laser procedure never became popular and ispresently used only infrequently.

It would be desirable to enable a substantially greater amount of lightenergy from long wavelength lasers to be used in an aqueous liquidenvironment to vaporize tissue without significant quantities of energybeing wasted by vaporizing the intervening aqueous liquid.

SUMMARY OF THE INVENTION

A laser energy delivery device of the present invention comprises anelongate hollow sheath having an open aperture at distal end portionthereof and a closed proximal end. The sheath defines a lumen, a gasinlet port and a gas outlet port that serves as the open aperture. Theopen aperture can be substantially coaxial with a laser energy conduitwithin the sheath or offset from the longitudinal axis therefrom. Thegas inlet port is spaced from the closed proximal end of the sheath andis in open communication with the lumen. The gas inlet port is adaptedfor connection to a source of a biocompatible gas such as air, argon,carbon dioxide, helium, nitrogen, and the like, or a combinationthereof.

A laser energy conduit, such as an optical fiber or an optical waveguide is disposed within the lumen of the sheath. The proximal end ofthe conduit extends through the closed proximal end of the sheath. Theproximal end of the laser energy conduit is adapted for connection to asource of a relatively long wavelength laser energy, i.e., at leastabout 1,300 nanometers and up to about 11,000 nanometers. The distal endof the laser energy conduit is positioned within the lumen of the sheathnear the open aperture. The distal end portion of the energy conduit isadapted to emit laser energy.

The laser energy delivery device can also include a handpiece at theproximal end of the sheath to facilitate handling and placement of thesheath and energy conduit. The gas inlet port can be spaced from thehandpiece or can be defined by the handpiece itself.

The distal end of the sheath can be flared out in a bell or funnel-likeshape, and can be beveled if desired. The distal end of the sheath, andits accompanying energy conduit, can be bent at an angle from the axisof the handpiece to facilitate placement of the open distal end of thesheath against the tissue that is to be irradiated by laser energy. Thelaser energy delivery device of the present invention is suitable fordelivering relatively long wavelength laser energy to a tissue in anaqueous medium with minimal loss of laser energy to the medium.

When an aqueous liquid is present at the tissue site, carbon dioxide orother biocompatible gas is infused into the sheath or handpiece andthrough the passageway defined between the optical fiber and the sheath,and displaces the liquid in the region between the distal end of thesheath and the adjacent tissue, creating a substantially liquid-freeregion between the distal end of the energy conduit, from which laserenergy is emitted, and the tissue. The substantially liquid-free regionenables a substantially greater portion of the laser energy to beutilized to vaporize the target tissue compared with irradiation throughan aqueous liquid that necessarily absorbs and dissipates at least someof the laser energy.

BRIEF DESCRIPTION OF THE DRAWING

In the drawings,

FIG. 1 is a chart showing the relative absorption in water of variouswavelengths of light energy;

FIG. 2 is an external view of an embodiment of the laser energy deliverydevice of the present invention;

FIG. 3 is an external view of an alternative embodiment of the device ofFIG. 2;

FIG. 4 is a partial, cross-sectional view of the distal end portion ofan embodiment of the device of FIG. 3;

FIG. 5 is a partial cross-sectional view of a preferred embodiment ofthe device of the present invention;

FIG. 6 is a partial external view of the device of FIG. 5, positionedwithin the male urethra for the treatment of a urinary blockage due toan enlarged prostate;

FIG. 7 shows an alternate embodiment of the present invention, partly insection;

FIG. 8 is an enlarged section view of the distal end portion of a deviceembodying the present invention;

FIG. 9 is a sectional view taken along plane 9-9 in FIG. 8; and

FIG. 10 shows in section yet another distal end portion of a deviceembodying the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

while this invention is susceptible of embodiment in many differentforms, there are shown in the drawings and are described in detailherein specific embodiments of the invention, with the understandingthat the present disclosure is an exemplification of the principles ofthe invention and is not limited to the specific embodimentsillustrated.

In the device and method of present invention, air or anotherbiologically compatible gas, such as argon, carbon dioxide, helium,nitrogen, or a mixture thereof, preferably carbon dioxide, is infusedinto a sheath disposed over a laser energy conduit such as an opticalfiber or optical wave guide, and displaces liquid at the distal end ofthe sheath. Light energy from a laser that is optically coupled to thelaser energy conduit is emitted at a wavelength of at least about 1,300nanometers (referred to herein as long wavelength laser energy, or LWlaser energy) from the distal end of the laser energy conduit. Theentire sheath has an inside diameter slightly larger than the outsidediameter of the optical fiber or wave guide. Preferably, the distal endportion of the sheath has an inside diameter somewhat larger than theinside diameter of the body of the sheath. In a particularly preferredembodiment, the distal end portion of the sheath is flared outwardlyinto a funnel or bell-like shape. Preferably the LW laser energy has awavelength in the range of about 1,300 nanometers to about 11,000nanometers.

When the laser energy delivery device of the present invention is usedto vaporize tissue in a duct, hollow organ, body cavity, or surgicallycreated passageway, which is filled with a biologically compatible,clear aqueous liquid, the distal end of the sheath is brought intocontact with, or close to, the target tissue. A biologically compatiblegas is infused through the sheath to displace the liquid between thedistal end of the optical fiber and the target tissue, creating a gasbubble therebetween. As a consequence, the target tissue is vaporized,ablated, or cut without wasting the laser energy by vaporizing theaqueous liquid.

FIG. 1 illustrates the relative absorption of various wavelengths oflight energy in water, according to Y. Hashishin and U. Kubo in“Development of Laser Endoscope for Coagulation and Incision,” publishedin Lasers in the Musculoskeletal System, Pg. 81-84, Springer VerlagBerlin (2001). As FIG. 1 shows, light energy from Holmium: YAG, Erbium:YAG, CO, and CO₂ lasers is highly absorbed by water.

FIG. 2 illustrates a laser energy delivery system, which includes a LWlaser energy source 110, capable of providing continuous wave, gated, orpulsed laser energy at a wavelength in the range of about 1,300 to about11,000 nanometers, and which is optically connected to a preferred longwavelength laser energy delivery device 10 of the present invention.Laser energy conduit 130 extends through handpiece 140, which isprovided to facilitate the handling of laser energy conduit 130. Theproximal end of laser energy conduit 130 includes a coupler 120, adaptedfor connection to a long wavelength laser energy source 110. Handpiece140 includes luer lock 150, which is in open communication withhandpiece 140 and gas supply tube 160. Gas supply tube 160 is removablyattached to luer lock 150, and allows transport of air or otherbiologically compatible gas from a supply source (not shown) intohandpiece 140. Sheath 170 extends from within the distal end ofhandpiece 140 and defines a lumen through which laser energy conduit 130extends. The distal end portion 180, of sheath 170, is open and allowsgas that is infused into sheath 170 through luer lock 150 to exit sheath170 at its open distal end.

Sheath 170 can be made of any biologically compatible rigid orsemi-rigid material. Preferably, sheath 170 is made of stainless steel,a rigid or semi-rigid plastic material, or a flexible, shape-memorynickel-titanium alloy such as nitinol, available from Memry, Inc.,Bethel, Conn. Suitable semi-rigid plastic materials include polyvinylchloride, block polyether amides, and the like materials. Distal endportion 180 of sheath 170 can be made of the same material as sheath 170or a different material such as a natural or synthetic rubber materialor a soft plastic material to facilitate safe contact with biologicaltissue. Alternatively, distal end portion 180 of sheath 170 can becoated with a natural or synthetic rubber.

FIG. 3 illustrates a preferred embodiment of the present invention. Indevice 15, the distal end portion consists of an outwardly flared distalend portion 190, instead of being cylindrical as shown in FIG. 2. Flareddistal end portion 190 can be a continuation of sheath 170 or can be aseparate piece that is fixedly attached to the distal end of sheath 170.Sheath 170 and its flared distal end portion 190 can be made of the sameor different materials as described for the embodiment depicted in FIG.2.

FIG. 4 is a partial, cross-sectional view of another preferredembodiment of the LW laser energy delivery device of the presentinvention. Device 20 includes a handpiece 220, defining port 222 andchamber 224, and a sheath 230. Sheath 230 is fixedly attached to thedistal end of handpiece 220 and defines a lumen 232 which is in opencommunication with chamber 224. Sheath 230 includes a distal end portion240, which has a larger inside diameter than the inside diameter of theremaining portion of sheath 230. Laser energy conduit 210 extendsthrough handpiece 220, chamber 224 and lumen 232. The distal end 212 oflaser energy conduit 210 is positioned approximately at the open distalend 242 of sheath 230. The laser energy conduit 210 is adapted at itsproximal end for connection to a LW laser energy source (not shown).Laser energy conduit 210 forms a liquid and gas-tight seal with thehandpiece 220 in the region 226 where the conduit 210 extends into thechamber 224.

Needle valve 254 is sealably attached to port 222 of handpiece 220. Knob252 is operably attached to needle valve 254 such that turning knob 252in a clockwise direction, for example, seals the needle valve 254 in aclosed position. Subsequently, turning knob 252 in a counter-clockwisemanner moves needle valve 254 to an open position. Luer lock 260 defineschannel 262 and is joined to the proximal end of the needle valve 254.When needle valve 254 is in the open position, channel 262 of luer lock260 is in open communication with port 222 and chamber 224 of handpiece220 and with lumen 232 of sheath 230.

FIG. 5 illustrates a particularly preferred embodiment of the presentinvention. Laser energy conduit 310 in device 30 extends throughhandpiece 320 and is fixedly attached thereto. Sheath 330 extends intohandpiece 320 and is attached to handpiece 320 by an adhesive or likeexpedient. Sheath 330 is bent at an angle φ from axis A of handpiece320. Sheath 330 can be made, for example, from stainless steel, a rigidor semi-rigid plastic, or a shape-memory nickel-titanium alloy, such asnitinol, or a combination of any of these materials.

When sheath 330 is made of stainless steel, the angle φ at which thesheath 330 can be bent is limited by the relative outside diameter ofsheath 330 and the inside diameter of an endoscope through which sheath330 will be positioned when the device 30 is used. When sheath 330 ismade of a flexible, shape-memory alloy, or a flexible or semi-rigidplastic, bend angle φ of sheath 330 can be in the range of about 20° toabout 120° from axis A, preferably in the range of about 30° to about90° from axis A.

When sheath 330 is made of a flexible material such as a flexible orsemi-rigid plastic, or a flexible shape-memory alloy, angle φ willdiminish when sheath 330 is constrained within an endoscope channel.When sheath 330 is extended through an endoscope channel, angle φ willincrease as distal end portion 340 of sheath 330 emerges from the distalend of the endoscope channel. Sheath 330 is preferably made of anickel-titanium shape-memory alloy such as nitinol.

In device 30, sheath 330 defines a lumen 332 and an opening 350 spacedfrom handpiece 320. Fitting 360 including port 370 forms a liquid andgas-tight seal around sheath 330 and is positioned around sheath 330such that port 370 is in open communication with opening 350 of sheath330. Luer lock 380 is secured to port 370 so that luer lock 380 and port370 are in open communication with the lumen 332 of sheath 330.

As shown in FIG. 5, flared distal end portion 340 of sheath 330 isbeveled so that the open end 342 of sheath 330 is roughly parallel toaxis A of handpiece 320. Button 390 on handpiece 320 is positioned toindicate the direction of the bend of sheath 330.

FIG. 6 illustrates sheath 330 of device 30 (FIG. 5) positioned for usein the treatment of a urethral restriction due to an enlarged prostate.Sheath 330 extends through channel 410 of endoscope 400. Endoscope 400is positioned within the male urethra 420, just proximal to prostrate430. Flared distal end portion 340 of sheath 330 is positioned tocontact the inner surface of urethra 430 over lobe 440 of prostate 430.The flared distal end portion 340 of sheath 330 is beveled at an angle,as described above. The bevel angle of the flare is selected tocomplement the angle of the bend in sheath 330, enabling the flareddistal end portion 340 of sheath 330 to efficiently contact the innersurface of urethra 420 at contact zone 450.

In use, a biocompatible gas, such as air, nitrogen, helium, argon,carbon dioxide, or mixtures thereof is infused through sheath 330 todisplace surrounding liquid and create gas bubble 460 within and aroundthe contact zone 450. Excess gas bubbles 480 are shown escaping frommain gas bubble 460. The gas bubble 460 displaces fluid from the contactzone 450, creating a fluid-free region through which LW laser lightenergy can pass with relatively little loss. Light energy from a LWlaser can then be emitted from the distal end portion 340 of sheath 330through laser energy conduit 310 (not shown) positioned within sheath330 as described above. Very little gas is required to displace thefluid at contact zone 450, and excess gas bubbles 480 escape from gasbubble 460 at contact zone 450 and can be absorbed by the surroundingfluid.

Clearance of fluid from contact zone 450 allows the LW laser energy toefficiently ablate or vaporize tissue from the underlying lobe 440 ofprostate 430. Flared distal end portion 340 of sheath 330 can be movedalong lobe 440 or 470, and gas can be infused as LW laser energy isemitted. Alternatively, when sufficient tissue has been removed fromcontact zone 450 by laser irradiation, the flared distal end portion 340of sheath 330 can be repositioned to form another contact zone 450 withlobe 440 or lobe 470 of prostate 430, and gas can be infused and LWlaser energy again can be applied to the tissue as needed, to clear theurethral restriction within the prostate 430.

FIG. 7 illustrates another embodiment of the present invention. Device50 is similar to device 20 shown in FIG. 4, except that instead ofdelivering laser energy forwardly, the distal end surface 522 of opticalfiber 510, which extends from the source of laser energy 110 throughhandpiece 520 and sheath 530, has been beveled at an angle of about 35°to 45°, preferably about 38° to 42°, into a prism-like shape and laserenergy is delivered from one side of the device via laser energy port532 in the sidewall of sheath 530 at the distal end portion thereof.

Plastic cladding and buffer coat 524 encloses and protects optical fiber510. Plastic cladding and buffer coating 524 preferably are made ofvinyl and a polyfluorocarbon (Teflon®), respectively, but may be made ofa variety of other materials, as known in the art. In this embodiment,plastic cladding and buffer coat 524 have been removed from the distalend portion of optical fiber 510, and the bared end portion of opticalfiber 510 is encased within quartz or fused silica capillary tube 528.

The proximal end of capillary tube 528 is fixedly attached about theproximal bared portion of optical fiber 510 by thermal fusing or anadhesive, as known in the art. Capillary tube 528 creates an airenvironment (which has a refractive index of 1) about the prism-like,beveled distal end face 522 of a quartz or fused silica optical fiber510 (which has a refractive index of 1.46). The higher refractive indexof the quartz or fused silica fiber is necessary for total internalreflection of light energy. In water, whose refractive index is 1.33,the difference in refractive indexes is not sufficient to cause thiseffect.

Sheath 530 extends from the distal end of handpiece 520 over opticalfiber 510 and terminates in rounded or blunt end portion 542, which mayalternatively be made into a sharp point or a syringe-like shape forease of penetration of tissue. Side port 532 in sheath 530, opposite thelaser emitting, beveled end surface 522 of optical fiber 510, permitsthe laser energy conveyed to beveled end surface 552 to exit sheath 530laterally, at an angle of about 70° to 90°, from the longitudinal axisof the device as shown by dotted lines 529.

A biocompatible gas, such as carbon dioxide, concurrently infusedthrough luer port 562 of luer fitting 560 into sheath 530, flows throughchannel 534 and exits through port 532, displacing aqueous irrigationliquid that surrounds the tissue to be vaporized, blood and bodilyliquids from the region between the laser emitting surface 526 ofcapillary tube 528 and the tissue to be affected, reduction orelimination of the loss of laser energy is achieved, which reduction orloss would otherwise occur in vaporizing the intervening liquid,increasing the tissue ablation efficiency of the device. Button 538 onthe side of handpiece 520 opposite the direction of emission of laserenergy energizes laser source 110 and indicates visually and tacitly tothe operator the direction in which laser energy will be emitted whenbutton 538 is depressed.

A layer or coating of reflective material 540 extends over about 30° to280°, preferably about 600° to 240°, of the back or non-laser energyemitting surface of capillary tube 528 and reflects stray laser energyand laser energy back-scattered from the target tissue back out throughside port 532 in sheath 530. Reflective material 540 can be gold,silver, copper, a dielectric or other material which efficientlyreflects the wavelength of laser energy being used. For reflecting laserenergy at wavelengths of 800 to 1200 nanometers, gold is preferred.Silver is preferred for reflecting laser energy at wavelengths of 1800to 2200 nanometers, as it is about as efficient in reflecting suchwavelengths of laser energy as gold and is less expensive.

As shown in FIG. 8, device 60 utilizes optical fiber 610, from whosedistal end portion buffer coating and vinyl cladding 624 have beenremoved. The distal end surface 622 of optical fiber 610 has beenbeveled at an angle of 35° to 50° preferably about 38° to 42° into aprism-like shape. Optical fiber 610 is held centered within of sheath630 by spacers 650, 652 and 654, as shown in more detail in FIG. 9. Inthis embodiment, the distal end 642 of sheath 630 is made into asyringe-like shape to facilitate tissue penetration. The distal end ofsheath 630 is closed with plug 644 of an adhesive or other material, asknown in the art, to prevent tissue from entering the distal end ofsheath 630. The distal end 642 of sheath 630 can also be made into asharp point or a blunt or rounded shape. A layer of reflective material640 reflects stray energy outwardly via side port 632.

No capillary tube is needed to maintain an air environment about beveledend surface 622 of optical fiber 610, if a biocompatible gas, such ascarbon dioxide, is continuously infused through space 634 between theexterior of optical fiber 610 and the interior of sheath 630. The gasflows over beveled distal end surface 622 of optical fiber 610, creatinga gas envelope thereabout, as well as displacing any aqueous liquidsfrom the space between the laser energy emitting surface of opticalfiber 610 and the target tissue. The emitted laser energy exits via sideport 632.

FIG. 9 is a cross-sectional, end view of device 60 of FIG. 8 taken atplane 9-9. As shown, three spacers 650, 652 and 654 hold optical fiber610 within the center of sheath 630, but allow space for a gas to flowover the distal, beveled end surface 622 of optical fiber 610 and outside port 632 of sheath 630, In addition to creating a gas environmentabout beveled surface 522 of optical fiber 610, a gas stream passing outof side port 632 of sheath 630 displaces aqueous irrigation liquid,blood and other bodily liquids from the space between the laser energyemitting surface of optical fiber 610 and the target tissue, avoiding orat least minimizing the loss of energy and ablative efficiency thatwould occur if such a gas was not infused through space 634.

As illustrated in FIG. 10, device 70 includes sheath 730 with closeddistal end 742 and optical fiber 710, opposite whose distal end a shortsection of light transmissive material 715 is positioned. Lighttransmission material 715 preferably has an index of refractionsignificantly higher than water or saline (which have a refractive indexof 1.33). Preferred materials include, for example, synthetic sapphire(which has a refractive index of about 1.745) and silica doped withmetal oxides, such as SFL-57, made by Schott Glass Technologies, Inc.Duryea, Pa. (which has a refractive index of about 1.811). Reflectivelayer 740 on the inside of sheath 730 reflects stray layer energy towardside port 732.

The use of such high-refractive index materials is described in co-ownedU.S. Pat. No. 5,496,309, which is incorporated herein by reference tothe extent pertinent. Material 715 may be held in place opposite thedistal end of optical fiber 710 by band or sleeve 717, which may be madeof a heat-shrinkable plastic or a plastic or metal fitting sized toaccommodate the distal end of optical fiber 710 and the proximal end ofmaterial 715, which may be fixed therein by an adhesive or crimping orboth. The distal end surface 722 of material 715 is beveled at an angleof about 35° to 50° preferably about 38° to 42° creating a prism-likeshape.

When a gas, such as carbon dioxide, is continuously infused throughspace 734 between the exterior of optical fiber 710 and the interior ofsheath 730 and flows over material 715 and out of side port 732 ofsheath 730, it displaces aqueous irrigation liquid, blood and other bodyliquids from the space between the laser energy emitting surface ofmaterial 715 and the target tissue, thereby minimizing the loss ofablative efficiency that would otherwise occur. Since the refractiveindex of one of the preferred materials 715 described above issignificantly higher than that of water or saline, a gas environmentabout beveled distal end surface 722 of material 715 is not required toachieve total internal reflection. However, such a device functions moreefficiently in a gas environment than in water or saline, due to thelower refractive index of the gas.

As shown in FIG. 10, an optional balloon 719 is disposed over the distalend portion of sheath 730 and occludes side port 732. The distal end 742of sheath 730 is rounded or blunt. Balloon 719 may be fixedly attachedto the exterior of sheath 730 by an adhesive, by friction, or by othermeans known in the art. Alternatively, balloon 719 may be removeablyattached to the exterior of sheath 730 by a tacky adhesive and the like.Balloon 719 is made of material which is transmissive of or transparentto the wavelength of laser energy to be used.

When a biocompatible gas is infused through space 734 between theexterior of optical fiber 710 and the interior of sheath 730 and flowsover material 715 and out of side port 732 in the distal end portion ofsheath 730, it inflates balloon 719. When balloon 719 of device 70 isbrought into contact with the target tissue and inflated, balloon 719,in turn, displaces aqueous irrigation liquid, blood and other bodilyliquids from the space between the balloon and the target tissue. Thelaser energy conveyed by optical fiber 710 passes through balloon 719 tothe target tissue and, since the intervening aqueous liquids have beendisplaced, substantially no loss of laser energy occurs.

Balloon 719 can be removed from the device after each use, thus device70 can be sterilized and a new, sterile balloon can be attached to theexterior of sheath 730. In this manner device 70 can be reused, reducingcost to the user.

Also, when inflated, balloon 719 spaces device 70 a specific distanceaway from the target tissue, allowing the laser energy beam to divergeand affect a greater area of the target tissue in a more uniform manner.Balloon 719 may also be employed with device 50 of FIG. 7 or device 60of FIG. 8 (provided its distal end is rounded or blunt) to achieve thesame objectives.

The devices illustrated in FIGS. 7 and 10 can, for example, be insertedthrough an endoscope into the male urethra to vaporize excess tissue ofan enlarged prostate gland to treat benign prostatic hyperplasia (BPH)or into the female uterus to coagulate the endometrial lining of theuterus to treat excessive bleeding, a procedure called endometrialablation. The device of FIG. 8 can, for example, be introduced into thelobes of an enlarged prostate gland to interstitially vaporize excesstissue, without damaging, except for the puncture, the sensitiveurethra. Such a device can also be introduced, for example, into a solidtumor and rotated while emitting laser energy like a beacon to coagulateor vaporize the tumor.

The devices and methods of the present invention can be utilized throughan endoscope in a liquid medium to rapidly vaporize, ablate, resect orcoagulate tumor tissue or non-malignant fibroid tissue in the femaleuterus, coagulate the surface of the uterus to treat menorrhagia, or tovaporize or coagulate tumor tissue elsewhere in the body, including thekidney, stomach or other organ. Using a device of the present inventionLW laser light energy can effectively coagulate bleeding vessels at alower level of laser energy than conventional laser devices, enablingthe devices of the present invention to be used, after the vaporizationor resection procedure, to coagulate or cauterize any remaining bleedingvessels. Lower energy laser energy can also be used to shrink tissues,for example, the nucleus pulposa or annulus of a spinal disc.

The present invention also provides a method of delivering relativelylong wavelength laser energy to a body tissue in an aqueous liquidmedium. The method involves positioning a laser energy delivery deviceof the present invention in a body lumen or cavity such as the madeurethra, the female uterine cavity, a blood vessel, or a surgicallyprepared channel. The device is positioned so that the distal end of thedevice is in contact with a tissue site to be irradiated with laserenergy. A gas supply source, operably linked to the gas inlet portprovides a stream of biologically compatible gas through the lumen ofthe device sheath, which exits the lumen at its open distal end incontact with the tissue. The gas is supplied at a pressure and flow ratesufficient to displace the aqueous fluid medium surrounding the tissuesite at the point of contact with the distal end of the sheath andmaintain a substantially liquid-free zone between the distal end of thelaser energy conduit component of the device and the tissue to betreated.

In a preferred embodiment, the method comprises the steps of:

(a) providing an endoscope defining at least one channel having an opendistal end and an open proximal end;

(b) providing a source of long wavelength laser energy, a laser energydelivery device of the present invention operably coupled to the sourceof laser energy, and a source of biocompatible gas operably connected tothe laser energy delivery device;

(c) positioning the endoscope within a body tissue lumen or cavity suchthat the open distal end of the endoscope channel is disposed oppositeor near a tissue site in need of laser energy treatment;

(d) positioning the laser energy delivery device through the endoscopechannel such that the distal end of the device extends through the opendistal end of the endoscope channel and contacts a body tissue site inneed of laser energy treatment;

(e) supplying gas from the source of biocompatible gas through the laserenergy delivery device to the tissue site at a pressure and flow ratesufficient to displace liquid from the tissue site in contact with theopen distal end of the sheath and maintain a substantially liquid-freeregion between the distal end of the laser energy conduit and the bodytissue; and

(f) supplying long wavelength laser energy from the laser energy sourcethrough the substantially liquid-free region to the tissue for a periodof time and at a laser energy intensity sufficient to treat the tissue.

The devices of the present invention can be used for treatments such asto effectively fragment or vaporize stones in the urinary tract (aprocedure called lithotripsy), to vaporize bone of the lamina or otherextensions of the vertebra to open the foraminal space in the spine andenable a portion of a herniated, ruptured or degenerated spinal disc tobe vaporized or, at a lower energy level, to be shrunk, to clear aurethral restriction due to an enlarged prostate, to vaporize orcoagulate tumor tissue, to cauterize tissue, and the like.

Sources of laser energy useful in conjunction with the device and methodof the present invention include filtered, third harmonic Nd: YAGlasers, emitting at about 1,440 nanometers, Holmium: YAG lasers and thelike, emitting at about 2,100 nanometers, Erbium: YAG lasers and thelike, emitting at about 2,940 nanometers, carbon monoxide (CO) lasers,emitting at about 6,000 nanometers, and carbon dioxide (CO₂) lasers,emitting at about 10,600 nanometers.

A preferred source of laser energy is the 80 watt Omnipulse™ MAXHolmium: YAG laser manufactured by Trimedyne, Inc. of Irvine, Calif.This laser emits light energy at a wavelength of about 2,100 nanometers,in pulses with a duration of about 250 to 350 microseconds, with arepetition rate up to 60 pulses per second. The peak energy output ofthe Omnipulse™ MAX is up to about 3.5 joules per pulse at a repetitionrate of about 23 pulses per second (up to about 7 joules per pulse inthe Double Pulse™ mode at a repetition rate of about 11 pulses persecond).

Typically, a source of laser energy having a wavelength in the range ofabout 1,300 to about 2,500 nanometers is optically coupled to a laserenergy conduit such as an optical fiber or, through mirrors mounted onan articulated arm, to a hollow waveguide. Ordinary quartz or fusedsilica optical fibers may be used with Alexandrite lasers, but opticalfibers with a low hydroxyl content, called “low OH” optical fibers, suchas manufactured by the 3M Company of St. Paul, Minn., must be used withHolmium lasers. Laser energy of wavelengths of in the range of about2,500 nanometers to about 11,000 nanometers is best delivered through aseries of mirrors attached to an articulated arm, to whose distal end ashort length of hollow waveguide or an optical fiber of a specialcomposition, such as sapphire, zirconium fluoride (ZrF₄), chalcogenide(As₂S₃), and the like, is attached.

In one preferred embodiment, to facilitate handling of the opticalfiber, the handpiece is disposed about 5 to 40 cm, preferably about 10to 30 cm, from the distal end of the optical fiber. The sheath extendsover the laser energy conduit from within the distal end of thehandpiece to the distal end of the laser energy conduit. The sheath canbe made wholly of metal or plastic or may consist of a metal shaft withan attached soft plastic distal end, a semi-rigid plastic shaft with anattached soft plastic distal end, or a semi-rigid plastic shaft with anattached metal distal end.

The gas inlet port in the sheath or handpiece enables carbon dioxide orother biologically compatible gas to be infused through the spacebetween the exterior of the optical fiber and the interior of thesheath. The sheath can have an inside diameter larger than the outsidediameter of the optical fiber, the distal end portion of the sheath mayhave a somewhat larger diameter than its shaft, or the distal endportion of the sheath can be flared-out into a bell or funnel-likeshape.

Flaring-out the distal end of the sheath reduces the risk of the lightenergy inadvertently striking and burning the distal end of the sheathand creates a reservoir of gas at its distal end. The flared-out endportion of the sheath can be about 0.3 to 2 cm in length, preferablyabout 0.5 to 1.5 cm long, and can have an inside diameter in the rangeof about 1.5 to about 5 times the outside diameter of the optical fiber,preferably about 2 to about 3 times the outside diameter of the opticalfiber.

The proximal end of the laser energy conduit of a device of the presentinvention is optically coupled to an appropriate laser energy source.The energy transmitted from the laser source through the energy conduit,such as an optical fiber or hollow waveguide, can be used, for example,to vaporize or resect (cut into sections) an enlarged prostate glandthat is blocking urine flow through the urethra, or to vaporize bone toopen the foraminal space in the spine.

Typically, for treatment of enlarged prostate, an endoscope is insertedinto the urethra through the penis and the distal end of the endoscopeis positioned near the prostate. A liquid, such as sterile water,saline, a glucose or dextrose solution, or other clear liquid is infusedinto the urethra through the distal end of the endoscope. Alternatively,the clear liquid can be simultaneously infused and withdrawn(circulated) to carry away debris and maintain a clear field of view atthe distal end of the endoscope. The sheath and optical fiber portion ofthe device of the present invention is extended through a channel in theendoscope, such that the distal ends of the optical fiber and the sheathproject outwardly from the open distal end of the endoscope channel andthe distal end of the sheath contacts the tissue to be irradiated.

A biocompatible gas, such as carbon dioxide, is infused through the gasinlet port and into the lumen of the sheath. A gas bubble at the opendistal end of the sheath creates a gas “cavity” between the tissue thatis to be irradiated and the distal end of the optical fiber. Lightenergy from the laser is emitted from the distal end of an opticalfiber, passes through the gas cavity and into the tissue, where the longwavelength laser energy vaporizes or ablates the tissue. The gas bubbleat the distal end of the sheath prevents the aqueous liquid around thetissue from absorbing laser energy being emitted from the optical fiber.It has been found that the use of a gas bubble enhances tissuevaporization by laser energy up to 1.9 times as compared to vaporizationwithout a gas bubble.

In vitro testing, a device constructed as described herein and shown inFIG. 5 was used to vaporize tissue submerged in a water bath. WhenHolmium: YAG laser energy at a wavelength of 2.1 microns was applied(24,000 Joules over 5 minute period), the vaporization rate was 1.4 to1.9 times greater with nitrogen gas concurrently infused through thedevice than without infusing the gas, using the same amount of energyfor the same period of time in both cases. The experimental data isshown in Table I, below. TABLE I ABLATION RATE INCREASE IN TISSUE(grams/min.) ABLATION % TYPE No Gas flow Gas flow RATE INCREASE Chicken0.519 0.910 0.391 75.3 Veal 1.059 1.520 0.461 43.5 Pig Prostate 0.4090.750 0.341 83.4

-   Laser: Omnipulse™ MAX@80 watts, 26 Hertz, 3.077 J/pulse-   Duration: 5 minutes-   Irrigation water: 1.2 ml/minute during lasing

Numerous variations and modifications of the embodiments described abovecan be effected without departing from the spirit and scope of the novelfeatures of the invention. No limitation with respect to the specificapparatus illustrated herein is intended or should be inferred. Theappended claims are intended to cover all such modifications as fallwithin the scope of the claims.

1. A non-linear optical active material for a non-linear optical devicecomprising: a matrix material; carbon nanotubes dispersed in the matrixmaterial; and chromophores having non-linear optical properties attachedto defect sites on the carbon nanotubes.
 2. The material of claim 1,wherein the chromophores are selected from a group consisting ofpolymers, oligomers, monomers, dimers, organic molecules, atomicnanoclusters, nanowires, colloids and nanoparticles.
 3. The material ofclaim 1, wherein the chromophores are chemisorbed to the defect sites onthe carbon nanotubes.
 4. The material of claim 1, wherein thechromophores comprise organic dye molecules.
 5. The material of claim 4,wherein the organic dye comprises a phenazine dye.
 6. The material ofclaim 5, wherein the organic dye comprises PSF.
 7. The material of claim1, wherein the defect sites on the carbon nanotubes comprise a carboxylgroup or a C₁₋₆ alkyl group.
 8. The material of claim 7, wherein theC₁₋₆ alkyl group comprises a sec-butyl group.
 9. The material of claim1, wherein: the matrix material comprises a polymer matrix material; andthe carbon nanotubes are well dispersed in the polymer matrix material.10. The material of claim 9, wherein the polymer matrix material isselected from a group consisting of polyamide, polyester, polyurethane,polysulfonamide, polycarbonate, polyurea, polyphosphonoamide,polyarylate, polyimide, poly(amic ester), poly(ester amide), apoly(enaryloxynitrile) matrix or mixtures thereof.
 11. The material ofclaim 1 further comprising different types of chromophores attached tothe carbon nanotubes, wherein the different types of chromophores have apeak sensitivity to different radiation wavelengths.
 12. The material ofclaim 1, wherein: the matrix material comprises a flexible thin film ora flexible fiber that is formed on a substrate; and an overall stiffnessof the non-linear optical active material is determined by a stiffnessof the substrate.
 13. The material of claim 1, wherein the carbonnanotubes are aligned in a controlled manner in the matrix material. 14.The material of claim 1, wherein SuperNanoMolecular structurescomprising the carbon nanotubes with attached chromophores arenon-centrosymmeteric.
 15. The material of claim 1, wherein thechromophores are covalently bound to a predetermined number of defectsites controllably arranged on the nanotubes.
 16. The material of claim1, wherein the material has a controlled morphology.
 17. A non-linearoptical or electro-optical device comprising the non-linear opticalactive material of claim
 1. 18. The device of claim 17, wherein thedevice is selected from a group consisting of harmonic generators,frequency translation or mixing devices, optical memories, opticalmodulators, optical amplifiers, optical switches, directional couplersand waveguides.
 19. The device of claim 17, wherein the non-linearoptical active material is a thin film waveguide exhibiting a χ³ effect.20. The device of claim 17, wherein the non-linear optical activematerial is a thin film exhibiting a χ³ effect incorporated into anoptical switch.
 21. The device of claim 17, wherein the non-linearoptical active material is a thin film exhibiting a χ² effectincorporated into a device comprising thin film electrodes on the thinfilm, such that an optical beam can pass through the thin film and bedeflected.
 22. A method of making a non-linear optical active material,comprising: forming defect sites on carbon nanotubes; attachingchromophores having non-linear optical properties to the defect sites onthe carbon nanotubes; and incorporating the nanotubes and thechromophores into a matrix material.
 23. The method of claim 22, whereinthe chromophores are chemisorbed to the defect sites on the carbonnanotubes.
 24. The method of claim 22, wherein: the step of formingdefect sites comprises reacting the carbon nanotubes with an anionicinitiator thereby generating anions on the surface of the carbonnanotubes; and the step of attaching chromophores comprises covalentlybonding the chromophores to the anions.
 25. The method of claim 24,wherein the anionic initiator comprises an alkyllithium salt.
 26. Themethod of claim 25, wherein the alkyllithium salt is sec-butyllithiumwhich forms sec-butyl groups on the carbon nanotubes.
 27. The method ofclaim 22 wherein: the step of forming defect sites comprises reactingthe carbon nanotubes with an acid thereby generating carboxyl groups onthe surface of the carbon nanotubes; and the step of attachingchromophores comprises covalently bonding the chromophores to thecarboxyl groups.
 28. The method of claim 27, wherein the acid comprisesa mixture of sulfuric and nitric acids.
 29. The method of claim 22,wherein the step of incorporating the nanotubes and the chromophoresinto a matrix material comprises incorporating the nanotubes and thechromophores into a polymer matrix material.
 30. The method of claim 29,wherein the polymer matrix material comprises a flexible polymer thinfilm or a flexible polymer fiber.
 31. The method of claim 30, whereinthe step of incorporating the nanotubes and the chromophores into thepolymer matrix material comprises incorporating the carbon nanotubes andthe attached chromophores into the polymer matrix material byinterfacial polymerization.
 32. The method of claim 31, wherein thepolymer matrix material is selected from a group consisting ofpolyamide, polyester, polyurethane, polysulfonamide, polycarbonate,polyurea, polyphosphonoamide, polyarylate, polyimide, poly(amic ester),poly(ester amide), a poly(enaryloxynitrile) matrix or mixtures thereof.33. The method of claim 22, wherein the chromophores are selected from agroup consisting of polymers, oligomers, monomers, dimers, organicmolecules, atomic nanoclusters, nanowires, colloids and nanoparticles.34. The method of claim 33, wherein the chromophores comprise organicdye molecules.
 35. The method of claim 34, wherein the organic dyecomprises PSF.
 36. The method of claim 22, wherein the step of formingdefect sites comprises controllably functionalizing the carbon nanotubesto controllably form the defect sites on the carbon nanotubes.
 37. Themethod of claim 22, further comprising controlling a morphology of thenon-linear optical active material.
 38. The method of claim 22, furthercomprising incorporating the non-linear optical active material into anon-linear optical device selected from a group consisting of harmonicgenerators, frequency translation or mixing devices, optical memories,optical modulators, optical amplifiers, optical switches, directionalcouplers and waveguides.